Thalassemias

Thalassemias (thal-a-SE-me-ahs) are inherited blood disorders. "Inherited" means that the disorder is passed from parents to children through genes.

Thalassemias cause the body to make fewer healthy red blood cells and less hemoglobin (HEE-muh-glow-bin) than normal. Hemoglobin is an iron-rich protein in red blood cells. It carries oxygen to all parts of the body. Hemoglobin also carries carbon dioxide (a waste gas) from the body to the lungs, where it's exhaled.

People who have thalassemias can have mild or severe anemia (uh-NEE-me-uh). Anemia is caused by a lower than normal number of red blood cells or not enough hemoglobin in the red blood cells.

Overview

Normal hemoglobin, also called hemoglobin A, has four protein chains—two alpha globin and two beta globin. The two major types of thalassemia, alpha and beta, are named after defects in these protein chains.

Four genes (two from each parent) are needed to make enough alpha globin protein chains. Alpha thalassemia trait occurs if one or two of the four genes are missing. If more than two genes are missing, moderate to severe anemia occurs.

The most severe form of alpha thalassemia is called alpha thalassemia major or hydrops fetalis. Babies who have this disorder usually die before or shortly after birth.

Two genes (one from each parent) are needed to make enough beta globin protein chains. Beta thalassemia occurs if one or both genes are altered.

The severity of beta thalassemia depends on how much one or both genes are affected. If both genes are affected, the result is moderate to severe anemia. The severe form of beta thalassemia is known as thalassemia major or Cooley's anemia.

Thalassemias affect males and females. The disorders occur most often among people of Italian, Greek, Middle Eastern, Southern Asian, and African descent. Severe forms usually are diagnosed in early childhood and are lifelong conditions.

Outlook

Treatments for thalassemias have improved over the years. People who have moderate or severe thalassemias are now living longer and have better quality of life.

However, complications from thalassemias and their treatments are frequent. People who have moderate or severe thalassemias must closely follow their treatment plans. They need to take care of themselves to remain as healthy as possible.

Source: National Heart, Lung, and Blood Institute, National Institutes of Health.